1. Technical Field
This invention relates to apparatus for detecting strain and torque on various members, and more particularly to an apparatus and method for detecting strain and/or torque on a rotating member such as an input shaft of a transmission, and for generating optical signals in accordance with the sensed strain and/or torque without the use of slip rings and other devices commonly required in such applications.
2. Discussion
Strain gauges are used in a variety of applications to measure the strain and/or torque experienced by various members. Many such applications are in connection with the testing of various components of an automobile, such as various shafts and members used in engines and transmissions of motor vehicles.
In previous applications, it has generally been necessary to use some form of slip ring or like element which is attached to the rotating shaft being sensed. The slip ring generally receives electrical signals from electrical sensing elements. The slip ring transmits the electrical signals via brushes or other like components to test equipment where the electrical signals can be converted into useful information to indicate the strain and/or torque experienced by the member being sensed.
In many applications, such as with transmissions, it is desirable to measure the strain and/or torque experienced by, for example, an input shaft of the transmission during operation. With most transmissions used with motor vehicles, space is very limited adjacent the input shaft, thus making it difficult and, in some instances, impossible to use conventional slip rings. As will also be appreciated, the brushes used with slip rings are also subject to wear and thus require periodic replacement. Various forms of strain and/or torque sensing systems are disclosed in the following patents, the disclosure of each of which is hereby incorporated by reference:
U.S. Pat. Nos. 4,529,312, 4,630,354, PA1 4,767,164, 4,962,495, PA1 5,422,477, 5,438,882
It would therefore be highly desirable to provide some form of strain and/or torque sensing apparatus and method which is capable of being used with a wide variety of members, and particularly with a rotating member such as an input shaft of a transmission, without requiring the use of slip rings and other electromechanical devices. It would further be highly desirable if such an apparatus and method could be employed which makes use of optical signals which are not susceptible to electrical interference and other objectionable phenomena that previously developed sensing systems must be concerned with.
It would be further highly desirable if an apparatus and method for sensing strain and/or torque on rotating members could be provided which makes use of a minimum number of independent components which facilitate use in complex components, such as transmissions, where space is very limited.